just bought a new hds unit for my 27 sportcraft would like to get a nice thru hull transducer for it.i see in buckeyebobs post the air mar b60 was talked about what do you guys think.also while were on the subject I have a 19ft aluminum boat with the factory lowrance transom mount that will not mark above a fast idle.its a welded hull so there is no ribs in hull and I have moved it to angle forward and back with no results .its mounted about 10 inches up from the keel any thoughts thanks in advance for any help